The general objective of this project is to investigate the characteristics and applications of enzymes covalently linked to insoluble supports. Study of these insoluble enzyme derivatives could provide useful information of both theoretical and practical significance. Initially, glass would be used as the carrier because of its resistance to microbial attack and stability to changes in pH, solvent composition,and high pressures. Other carriers such as carboxymethylcellulose, polyaminostyrene, etc., might also be used. Attempts would be made to couple pronase, leucine aminopeptidase (EC 3.4.1.1.), and proline iminopeptidase (EC 3.4.14) to porous glass by means of an azo or thioure linkage. The dependence of the activity of these complexes on pH, temperature, solvent composition, and substrate structure would be investigated. The enzymes mentioned above possess specificities which make them appropriate for applications in protein chemistry. Pronase would be used for applications in complete protein hydrolysis. Enzymatic hydrolysis has the advantage that the hydrolysate represents an accurate description of amino acid composition since the undesirable side reactions of the conventional acid hydrolysis are eliminated. A mixture of insolubilized leucine amino peptidase and proline iminopeptidase could be used for the sequential analysis. The feature of enzyme insolubility would considerably reduce the technical difficulties inherent in these applications.